SK Group

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From textiles to AI chips, SK Group has grown into one of South Korea’s largest conglomerates.

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SK Group is a South Korean multinational conglomerate that operates more than 150 companies in industries including semiconductors, energy, and telecommunications. Headquartered in Seoul, SK Group is one of the country’s largest family-controlled conglomerates—known as chaebols—alongside Samsung, Hyundai Motor Group, and LG.

At the top of SK Group’s corporate structure is SK Inc., the group’s holding company. Chair Chey Tae-won owns a 17.9% stake in SK Inc., allowing the Chey family to exercise control over the group through the holding company rather than through direct majority ownership of its individual businesses.

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Chey Tae-won has led SK Group since 1998.

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In 2022, SK Group became South Korea’s second-largest conglomerate by assets, overtaking Hyundai Motor and trailing only Samsung. Much of its growth came from SK hynix, the world’s second-largest memory chipmaker and a leading supplier of high-bandwidth memory (HBM) chips used in artificial intelligence systems.

SK Group traces its origins to 1953, when founder Chey Jong-gun acquired Sunkyong Textiles after the Korean War. The company expanded its textile operations in the 1960s, building an acetate factory in 1968 and a polyester factory in 1969. Because the materials used in synthetic fibers are derived from petroleum, those investments helped lay the groundwork for Sunkyong’s later expansion into oil refining.

After Chey Jong-gun died in 1973, his younger brother, Chey Jong-hyon, took over the company and began expanding into petrochemicals and oil refining. Sunkyong sought to control more of its supply chain, from securing and refining petroleum to producing the materials used in its textile businesses.

Sunkyong also entered the hospitality business by acquiring the Walkerhill Hotel in 1973. In 1975, the company was renamed Sunkyong Ltd.

In December 1980, Sunkyong acquired a controlling interest in Korea Oil Corporation, then South Korea’s largest energy company. The acquisition greatly expanded Sunkyong’s energy business and helped establish it as one of the country’s largest conglomerates.

Sunkyong expanded into telecommunications in 1994, acquiring Korea Mobile Telecommunications Corp., the state-owned mobile carrier. The company introduced the world’s first commercial CDMA mobile phone service in 1996 and was renamed SK Telecom in 1997.

Sunkyong Group was renamed SK Group in January 1998 amid the 1997–98 Asian financial crisis, which led to bankruptcies and widespread restructuring among South Korea’s chaebols.

After Chey Jong-hyon died in 1998, leadership passed to his eldest son, Chey Tae-won. Under his leadership, SK Group continued to expand its energy and technology businesses. In 2007, the group adopted a holding-company structure, splitting SK Corporation into SK Holdings, which held stakes in group affiliates, and SK Energy, which took over its energy and chemicals businesses.

In 2012, SK Telecom acquired Hynix Semiconductor, which was renamed SK hynix, marking SK Group’s entry into the semiconductor industry. The acquisition was considered risky because semiconductor manufacturing is highly cyclical and requires substantial capital investment. SK hynix subsequently invested heavily in HBM, introducing the world’s first HBM product with Advanced Micro Devices (AMD) in 2014.

After initially struggling to build a market for the technology, the company continued developing HBM and eventually became the leading supplier of the memory chips used by NVIDIA (NVDA) in its AI accelerators. By 2026, SK hynix held a majority share of the global HBM market.

SK Innovation spun off its battery business in 2021 to create SK On. The following year, SK Group added $22 billion in U.S. investments in semiconductors, clean energy, and life sciences, bringing its planned U.S. investments through 2025 to $52 billion. Of the additional investment, $15 billion was earmarked for semiconductor research and development and an advanced packaging and testing facility, while about $5 billion was designated for clean-energy projects.

On July 10, 2026, SK hynix listed American depositary receipts (ADRs) on the Nasdaq. Priced at $149 each, the ADRs raised $26.5 billion for the company. The U.S.-listed receipts debuted at a 14% premium to SK hynix shares traded in Seoul, and the gap later widened to nearly 50%. By late August, the ADRs were still trading at a premium of about 30%. 

In 2003, Chey was sentenced to three years in prison for his role in a $1.3 billion accounting fraud involving an SK Group affiliate. He was released after seven months and received a presidential pardon in 2008.

In 2013, Chey was sentenced to four years in prison for embezzling 46.5 billion won (about $44 million at the time) from two SK Group affiliates and using the money for personal investments in stock futures and options. He served 31 months before President Park Geun-hye pardoned him in August 2015.

Chey’s divorce from Roh Soh-yeong, daughter of former South Korean President Roh Tae-woo, drew attention in part because of its potential effect on Chey’s control of SK Group. The couple married in 1988, but in 2015 Chey publicly disclosed that he had a child outside the marriage and said he intended to divorce Roh. He filed for divorce mediation in 2017. A court granted the divorce in 2022, but litigation over property settlement continued.

In October 2025, South Korea’s Supreme Court finalized the divorce but sent the ruling on the division of property back to a lower court for reconsideration. In July 2026, the Seoul High Court reconsidered the case and ordered Chey to pay Roh 944 billion won while allowing him to retain his shares in SK Inc., the holding company through which the Chey family controls SK Group. The ruling is subject to appeal.

Like other South Korean chaebols, SK Group has faced scrutiny over a corporate structure that allows a founding family to maintain control without owning a majority of the group’s shares.

Cross-shareholdings, in which affiliated companies own shares in one another, were historically one way chaebol families maintained such control, but South Korea substantially reduced the practice. The Fair Trade Act was amended in 2014 to prohibit new cross-shareholdings, and by 2018 the Korea Fair Trade Commission said the number of such arrangements had fallen 99.96% in five years.

Concerns about family control and the rights of minority shareholders are also part of a broader debate over the “Korea discount,” the tendency of South Korean stocks to trade at lower valuations than comparable companies in other markets. Corporate governance at chaebols is one proposed explanation, although research has also pointed to factors such as low shareholder returns, low return on equity, and limited growth prospects.